Paying out under tension of products in sheet form,particularly paper sheet



Nov. 19, 1968 E. TISON ET AL 3,411,684 PAYING OUT UNDER TENSION OFPRODUCTS IN SHEET FORM, PARTICULARLY PAPER SHEET Filed July 11. 1966APPLICANTS Eric Tison and Roger Blanchir BY Misegade's 8: DouglasATTORNEYS United States Patent.

3,411,684 PAYING OUT UNDER TENSION OF PRODUCTS IN SHEET FORM,PARTICULARLY PAPER SHEET Eric Tison, Paris, and Roger Blanchin, Stains,France, as-

signors to Societe anonyme dite: Seailles & Tisou, Paris, France, acompany of France Filed July 11, 1966, Ser. No. 564,259 Claims priority,application France, July 12, 1965, 24 321 6 Claims. (Cl. 22625) ABSTRACTOF THE DISCLOSURE In many technical fields it is necessary to supply amachine which operates in a continuous or discontinuous manner from aflexible sheet which is unrolled from a reel. Such is the case inparticular for the supply of paper sheets for printing machines.

In general, it is desirable to be able to maintain the tension of suchsupply sheets constant whatever may be their instantaneous speed oftravel. In particular, the webs of paper serving to supply printingmachines and above all those which exert on the paper web anoncontinuous pull, it is important in the majority of cases to maintainthe tension of the web constant at a predetermined value which is inparticular a function of the nature of the web and of the operatingconditions of the machine being supplied and which remains constant inspite of variations in the speed of travel, in particular possiblestoppages of the web.

In certain special cases, it may moreover be desirable to control thetension of the paper in accordance with a predetermined law as afunction of the mean speed of web.

The present invention relates for this purpose to a device forcontrolling the supply tension of a fiexible continuous sheet travellingto a machine, especially of a web of paper travelling to a printingmachine, comprising a guide assembly with at least one roll or rollerdisposed in the path of the sheet and driven by it, a torquetransmitting device establishing a mechanical connection between thisassembly motor which, characteristically, tends to drive the guideassembly with at least one roller in the opposite sense to that in whichit is effectively driven by the sheet.

The torque transmitting device (coupling) is a mechanical orelectro-mechanical device capable of transmitting a predeterminedtorque. characteristically, in its use in accordance with the invention,the coupling operates in the opposite direction to its normal directionof operation in which it transmits a driving torque from a motor: inthis case it efiectively transmits a torque which tends to oppose theadvance of the sheet, that is to say a resistive torque. In theseconditions, the coupling slip which has an angular value equal to thesum of the speeds of the coupling and the roller (in revolutions perminute) prevents at each instant an opposing tension torque equal tothat necessary to obtain slip. When the sheet stops, the roller stops,the coupling always rotates backwards and the stationary sheet is alwayssubjected "ice to a tension. It is to be noted that the tension torqueis independent of the angular value of the relative displacements of theroller and coupling, this value only causing a proportional heating ofmagnetic or mechanical origin.

The following description and the accompanying drawings, given above allby way of non-limiting example will make better understood how theinvention may be put into effect.

In the accompanying drawings:

FIG. 1 shows diagrammatically a sheet tensioning device in accordancewith the invention;

FIG. 2 illustrates the application of this device to a paper supplysystem for a printing machine;

FIG. 3 shows a variant of the installation of FIG. 2; and

FIG. 4 is a diagram of an electromagnetic coupling of a type known perse which may be used for the purposes of the invention.

In accordance with the invention, in order to maintain constant thetension of a web I, particularly a web of paper, which is drawn off in acontinuous or discontinuous manner in the direction of the arrow F theweb is made to pass over a roller 2 which turns in one direction on ashaft 2a under the motive action of the paper.

The shaft 2a of the roller is fixed to the rotor 3a (output) of acoupling 3 which moreover comprises a support casing 312 and a rotatingstator (input or control) 30.

When a motor 4, for example an electric motor, rotationally drives thestator 3c of the coupling in the direction of the arrow F for examplethrough the intermediary of a pulley 5 and a belt 6, this statorrotationally drives, through the intermediary of the coupling means, therotor 3a in the direction which tends to make the roller 2 turn in theopposite direction to that caused by the movement of the paper.

The coupling means which depends on the type of coupling used (frictioncoupling, powder-type electromagnetic coupling, or the like) wouldpreferably be a magnetic powder located in a space lying between thestator and the rotor of the coupling, this latter being then of theelectromagnetic powder-type, as for example the coupling made by theJaeger Company. FIG. 4 shows diagrammatically and entirely by way ofexample the principles of such a coupling and in it can be recognisedthe rotor 3a and the rotating stator 30 in a casing indicated by 3b. Thereference 3e indicates a clearance in which is located the magneticpowder which a coil 3d tends to orientate so as to form a more or lesscompact mass between the rotor and the stator when a current flowsthrough the coil. This current is fed to the coil by brushes or anyother appropriate means, and the electric wires 3 3g indicated in FIG. 4are only shown as an illustration of the conductors for supplyingcurrent to the coil of the coupling. Moreover, there is seen in FIG. 4 acontrol assembly 25 comprising in particular a potentiometer whichenables the supply conditions of the coil 3d to be varied andconsequently the value of the driving torque exerted on the rotor 3a bythe rotating stator 30 to be varied. In that the installation shown inFIG. 2 and in the installation shown in FIG. 3, the coupling is used insuch a manner that its rotor 3a is driven by the paper in the oppositedirection to the direction of normal rotation which the rotating statorSo would impress on this rotor under the action of the motor 4. Theresult of the two opposing actions exerted on the roller 2 by the web ofpaper and by the coupling gives to this web a constant tension the valueof which corresponds to the adjusted value of the torque of thecoupling. This constant tension is exerted throughout the movement ofthe Web 1, whatever the law of this movement and it is exerted duringstoppage of the band with the same value.

The possibility of adjusting the value of the driving torque of theelectromagnetic powder coupling of the type described veryadvantageously permits the corresponding adjustment, to any desiredvalue, of the tension of the paper web, independently of variations inits speed of travel. For example the tension may be adjustedproportionally to the square of the mean speed of the paper.

In the system illustrated in FIG. 2, the paper web 1 is unrolled from areel and thereafter passes over a roller 11 with a fixed axis and aroller 12 with a moveable axis mounted on an assembly of arms 13 asdisclosed in French Patent No. 1,356,991, filed on Feb. 7, 1963, in thename of the applicants. From the roller 12, the web 1 is returned to theroller 2 forming part of the tension regulating device in accordancewith the invention. Pressure rollers 7 apply the web 1 against theroller 2. A pair of opposed driving rollers 14 serve to drive the webfor the supply of the printing machine.

When the paper web stops, the roller 2 also stops but as the couplingrotates always in the opposite direction, the stationary paper is alwaysunder tension.

In the installation shown in FIG. 3, an absolute regulation of thetension of the paper is obtained. This installation comprises the sameelements as the installation shown in FIG. 2, indicated by the samereference numbers. Moreover, it comprises an assembly of two rollers(fixed) and 21 (moveable), which transmit mechanically through theintermediary of the moveable shaft 21a the tension of the paper to apick-up 22 which transduces it into an electrical magnitude. Thiselectrical magnitude is compared in a regulation system 23 which areference magnitude and the difierence which may exist between the twovalues is used to control the current which flows in the coil 3d of thecoupling.

In the figure, the regulation assembly comprising the system 23 and theconductors 24 connecting the pick-up 22 and the coupling 3 to thissystem have only been shown very diagrammatically bearing in mind thatthis reaction is a technique which is well-known in itself and which hasno need of being described in detail in the present text. It will beunderstood that the regulation system causes a variation of the value ofthe torque of driving of the rotor by the stator in such a sense thatthe tension of the web is rendered equal or substantially equal to thevalue corresponding to the reference magnitude.

It will also be understood that the electromagnetic powder-type couplingwhich is preferably used may however be replaced by a coupling ofanother type, of adjustable torque mounted in such a manner that thistorque tends to oppose the rotation of the roller in the sense sought bythe web.

What is claimed is:

1. A device for regulating the tension of a flexible continuous sheettraveling to a machine, such as a web of paper traveling to a printingmachine, comprising at least one roller disposed on the path of thesheet and driven by the sheet in one direction of rotation, a drivingmot-or, coupling means including a sli coupling, said coupling meanscoupling said driving motor to said roller to urge said roller to rotatein the opposite direction to that in which it is rotated by said sheet,said coupling comprising a rotor fixed to said roller, a rotatablestator drivably coupled to said motor and means for transmitting drivingtorque from said stator to said rotor, said means for transmitting adriving torque from said stator to said rotor comprising a magneticpowder and a coil for creating a magnetic field to which said powderbetween said rotor and said stator is subjected in accordance with thepassage of an electric current through said coil.

2. A device according to claim 1, and including a potentiometer foradjusting the value of the current passing through said coil in order toadjust the value of the driving torque of said coupling.

3. A device according to claim 1, and further comprising a tensionpick-up for transducing the tension of the sheet into an electricalmagnitude, regulating means for comparing said magnitude with areference magnitude and for controlling as a result of said comparisonthe value of the current flowing in said coil whereby to vary thetension of said sheet in order to reduce the difference between thevalue of the electrical magnitude and the value of said referencemagnitude.

4. A device according to claim 1, in which the pick-up co-operates witha moveable roller displaced by the sheet by an amount depending on thetension of said sheet.

5. A device for regulating the tension of a flexible continuous sheettraveling to a machine, such as a web of paper traveling to a printingmachine, comprising at least one roller disposed on the path of thesheet and driven by the sheet in one direction of rotation, a drivingmotor, coupling means including a slip coupling, said coupling meanscoupling said driving motor to said roller to urge said roller to rotatein the opposite direction to that in which it is rotated by said sheet,said coupling comprising a rotor fixed to said roller, a rotatablestator drivably coupled to said motor and means for transmitting drivingtorque from said stator to said rotor, and a tension pick-up sensitiveto the tension of the sheet and acting on the value of said drivingcouple to maintain this tension at a predetermined value.

6. A device for regulating the tension of a flexible continuous sheettraveling to a machine, such as a web of paper traveling to a printingmachine, comprising at least one roller disposed on the path of thesheet and driven by the sheet in one direction of rotation, a drivingmotor, coupling means including a slip coupling, said coupling meanscoupling said driving motor to said roller to urge said roller to rotatein the opposite direction to that in which it is rotated by said sheet,and pressure rollers for applying said sheet against said roller.

References Cited UNITED STATES PATENTS 2,658,751 11/1953 J aeschke226-195 2,748,299 5/1956 Weesner et a1 226195 X 2,748,329 5/1956 Allbertet al. 226-l X 2,945,637 7/1960 Derrick et al. 226 3,112,052 11/1963Johnson 22625 3,180,548 4/1965 Staflord 226-195 ALLEN N. KNOWLES,Primary Examiner.

